Stable Cosmetic Ink Composition

ABSTRACT

A cosmetic ink composition comprises a particulate material, a (meth)acrylic acid homopolymer or salt thereof, and a rheology modifier. The particulate material can have a Particle Size Distribution D50 of about 100 nm to about 2,000 nm. The (meth)acrylic acid homopolymer or salt thereof can have a weight average molecular weight of less than about 20,000 daltons. The rheology modifier can be selected from the group consisting of alkali swellable emulsion polymers, hydrophobically modified alkali swellable emulsion polymers, and combinations thereof. The cosmetic ink composition can have a first dynamic viscosity of greater than about 1,100 cP at a shear rate of 0.1 sec−1 measured at 25° C. and a second dynamic viscosity of less than about 100 cP at a shear rate of 1,000 sec−1 measured at 25° C.

FIELD OF THE INVENTION

Described herein is an ink composition for inkjet printing applications,and more particularly a cosmetic ink composition comprising aparticulate material that exhibits long-term stability while still beingsuitable for high frequency printing via thermal and/or piezo inkjetprintheads.

BACKGROUND OF THE INVENTION

Most printing applications are designed for printing onto whitesubstrates for document production or photo printing. For suchapplications, black inks are primarily used in combination with three ormore colored inks. Formulating stable black inks and colored inks iswell understood. For instance, it is known that molecular dyes willgenerally not exhibit settling over time if they are soluble in thecarrier. In addition, pigment-based black inks generally utilizeparticle sizes small enough to be suspended in low viscosity carriersand take advantage of both Stokes' Law and Brownian motion to keep theparticles suspended. However, these inks exhibit very low opacity, asdyes are transparent by nature and pigmented-based black inks useparticle sizes that are small enough to be suspended but are muchsmaller than the particle sizes required to scatter visible light. Foropacifying purposes, optimal light scattering occurs at half thewavelength of light. Since the visible light spectrum ranges from about400 to about 700 nm, the optimal particle size for opacification is fromabout 200 to about 350 nm. This is significantly larger than theparticle size of stable black pigment-based inks used in consumerprinting applications which generally comprise particles that are lessthan about 50 nm in size.

For cosmetic printing applications, it is known that the ink must besufficiently opaque to cover and/or hide skin imperfections. However, itis difficult to formulate an opaque stable ink which can be jetted dueto the particle size and levels needed to achieve opacity and thegravitational settlement of the large and/or dense particles used tocreate such inks. In particular, it is challenging to formulate a stableink comprising titanium dioxide, a commonly used white pigment, that issubstantially free of particle settling over the shelf-life of theproduct. While there are multiple industries that routinely use titaniumoxides in products which can demonstrate long-term stability, theseproducts generally have very high viscosities. For instance, sunscreensand traditional makeups and/or skin care products which are appliedmanually comprise titanium oxide particles and are stable; however, theyare only able to do so through viscosities that are orders of magnitudegreater than the viscosity of typical inkjet compositions and are notcompatible with inkjet printers and/or cartridges.

For many years, the inkjet printing industry has attempted to createstable white inks that can exhibit high frequency jetting, nozzlehealth, and/or drop placement accuracy. Current formulations utilizerheology modifiers and/or particle surface treatments to help slow thesettling rate of the particles. However, the time frame of the particlesuspension in such formulations is only on the order of days or weeks.This can be helpful for industrial applications where the printeroperator only needs to re-suspend the particles through agitation everyfew days, rather than every few hours. However, this does not enable aproduct to be sold to a consumer in a typical retail environment wherethe product may need to be stable for months or years as it passesthrough a supply chain and is used by a consumer. Other formulationapproaches have utilized titanium oxides with a smaller particle size toslow the rate of settling and/or have employed secondary particles suchas hollow spheres to help provide some opacity. However, suchformulations still settle within weeks, and the opacity is much lowerthan that of inks which use titanium oxides with particle sizes of 200nm or greater. Even the most stable current white inks demonstrateparticle settling over time if left undisturbed. Manufacturers of suchinks recommend vigorous shaking on a daily or weekly basis to redispersethe particles and/or recommend that these inks are recirculated duringuse.

As such, there is a need for an opaque inkjet ink composition withincreased particle suspension stability for consumer cosmeticapplications. In particular, there is a need for a cosmetic inkcomposition that comprises particles that are big enough to createopacity yet remain in suspension and has a viscosity that is compatiblewith inkjet printer cartridges and nozzle technology.

SUMMARY OF THE INVENTION

A cosmetic ink composition comprises: (a) a particulate material havinga Particle Size Distribution D50 of from about 100 nm to about 2,000 nm;(b) a (meth)acrylic acid homopolymer or a salt thereof having a weightaverage molecular weight of less than about 20,000 daltons; and (c) arheology modifier, wherein the rheology modifier is selected from thegroup consisting of alkali swellable emulsion polymers, hydrophobicallymodified alkali swellable emulsion polymers, and combinations thereof;wherein the cosmetic ink composition has a first dynamic viscosity ofgreater than about 1,100 cP at a shear rate of 0.1 sec⁻¹ measured at 25°C. and a second dynamic viscosity of less than about 100 cP at a shearrate of 1,000 sec⁻¹ measured at 25° C.

A cosmetic ink composition comprises: (a) from about 1 to about 30active weight (wt) % of a particulate material; (b) a (meth)acrylic acidhomopolymer or a salt thereof; and (c) from about 0.3 to about 1 activewt % of a rheology modifier, wherein the rheology modifier is selectedfrom the group consisting of a (meth)acrylate polymer, a (meth)acrylatecopolymer, and mixtures thereof; wherein the ink composition has a firstdynamic viscosity of greater than about 1,100 cP at a shear rate of 0.1sec⁻¹ measured at 25° C. and a second dynamic viscosity of less thanabout 100 cP at a shear rate of 1,000 sec⁻¹ measured at 25° C.

A cosmetic ink composition comprises: (a) a particulate material havinga Particle Size Distribution D50 of from about 100 nm to about 2,000 nm;(b) a (meth)acrylic acid homopolymer or a salt thereof having a weightaverage molecular weight of less than about 20,000 daltons; and (c) fromabout 0.3 to about 1 active wt % of a rheology modifier, wherein therheology modifier is selected from the group consisting of alkaliswellable emulsion polymers, hydrophobically modified alkali swellableemulsion polymers, and combinations thereof; wherein the ink compositionhas a first dynamic viscosity of about 1,100 cP to about 10,000 cP at ashear rate of 0.1 sec⁻¹ measured at 25° C. and a second dynamicviscosity of from about 10 to about 100 cP at a shear rate of 1,000sec⁻¹ measured at 25° C.

BRIEF DESCRIPTION OF THE DRAWINGS

While the specification concludes with claims particularly pointing outand distinctly claiming the present invention, it is believed the samewill be better understood from the following description taken inconjunction with the accompanying drawings in which:

FIG. 1 is an exploded view of a personal care device for use indepositing the cosmetic ink composition described herein; and

FIG. 2 is an exploded view of a cartridge containing the cosmetic inkcomposition described herein.

DETAILED DESCRIPTION OF THE INVENTION

As used herein, “active wt %” and “wt % (active)” refers to the amountof solid of an ingredient dissolved or suspended in water in thecomposition.

As used herein, “ambient conditions” refers to a temperature of about 23degrees Celsius (° C.) and 50% relative humidity (RH).

As used herein, “Particle Size Distribution D50” refers to the diameterwhere fifty percent of the distribution has a smaller particle size.

As used herein, “Particle Size Distribution D90” refers to the diameterwhere ninety percent of the distribution has a smaller particle size.

As used herein, “separation” refers to the formation of a clear fluidlayer at the top of a sample regardless of the uniformity of theparticles in the sample below the clear fluid layer. Separation caninclude particle settling and/or syneresis.

As used herein, “settling” refers to the falling of particles in acomposition due to gravity (according to Stokes' Law) to the bottom of acontainer. Particle settling can be affected by the size of theparticles and their agglomeration over time.

As used herein, “static storage” refers to storage of a composition inthe absence of vigorous or sustained vibration, agitation, or mixingprior to analysis or deposition of the composition.

As used herein, “syneresis” means phase separation, i.e. extraction orexpulsion of a liquid from a gel, in this case a weak colloidal gel. Theparticles in a composition exhibiting syneresis are still uniformlysuspended below the clear fluid layer.

As used herein, “ratio of (meth)acrylic acid homopolymer or a saltthereof to rheology modifier” refers to the ratio of the active wt % ofthe (meth)acrylic acid homopolymer or salt thereof divided by the activewt % of the rheology modifier.

As used herein, “the storage modulus” or “G”′ refers to the measure ofthe stored energy, representing the elastic portion of the composition.

As used herein, “the loss modulus” or “G” refers to the measure of theenergy dissipated as heat, representing the viscous portion of thecomposition.

As used herein, “weight percent as added” refers to the amount of thetotal active plus water as added to the composition.

As used herein, “zeta potential” refers to the electrokinetic potentialof the cosmetic ink composition.

As used herein, the articles “a” and “an” are understood to mean one ormore of the material that is claimed or described, for example, “arheology modifier” or “an active”.

All weights, measurements and concentrations herein are measured atambient conditions unless otherwise specified.

All percentages, parts, and ratios as used herein are based upon thetotal weight of the cosmetic ink composition, unless otherwisespecified. All such weights as they pertain to listed ingredients arebased on the level as added in the composition, unless otherwisespecified.

Cosmetic inks can require a white or light colored particulate materialcomprising particles large enough to be visually perceptible to thehuman eye in order to create opacity to cover skin imperfections.However, printing a cosmetic ink composition comprising a particulatematerial having a particle size large enough to be visually perceptiblecan be a challenge for current inks, printers, and/or cartridges. Thesechallenges are caused primarily by the settling of the large, denseparticles and secondarily by the packing of the settled particles in thecartridge. Re-mixing, either by automated mixing or hand shaking, maynot be compatible with consumer in-home or hand-held printing purposesbecause of the vigorous and repeated re-mixing needed to keep theparticles uniformly suspended.

Current opaque ink products can require repeated shaking, agitation,and/or rotation of the device and/or cartridge to keep the particles ina uniform suspension. This can be inconvenient to a consumer and is anadditional step that consumers may not perform as instructed. If theparticles are not re-dispersed, the cosmetic ink composition may not beuniform and/or the particles can become packed into the cartridge.Settling can be minimized by adding rheology modifiers to the ink.However, if the viscosity of the cosmetic ink composition is not wellcontrolled, clogging and the speed of flow through the microfluidicchannels and nozzles can make printing difficult. The use of dispersantsin cosmetic ink compositions may help control agglomeration (i.e. thesticking of particles to one another) and hard packing of the particles;however, such formulations still require shaking to re-disperse theparticles and do not exhibit particle suspension stability.

Described herein is a cosmetic ink composition that can exhibitlong-term particle suspension stability and a personal care device fordepositing the cosmetic ink composition. In one aspect, “stable whiteink” can refer to an ink substantially free from particle settling,where no agitation or mixing is required to use the ink for itsapplication.

In one aspect, the cosmetic ink composition described herein can bejetted onto any surface, preferably a keratinous surface including humanskin and/or hair.

The cosmetic ink composition can comprise a unique combination of arheology modifier and a (meth)acrylic acid homopolymer or a salt thereofthat can suspend a particulate material having particles large enough tobe visually perceptible, yet can still be jettable. Careful balancing ofthe agglomeration of the particles and viscosity of the cosmetic inkcomposition can be used to inhibit particle settling, providing particlesuspension stability beyond which has been previously reported withouthindering high frequency printing capabilities via thermal and/or piezoinkjet printheads. One advantage to this is that little to no shaking,and/or agitation of the cosmetic ink composition by the consumer orautomated mechanical processes before and/or during printing is neededto re-disperse the particles. This can make the cosmetic ink compositionmore user-friendly as it does not require the consumer to perform anadditional step to re-disperse the particles and/or can eliminate theneed for agitation or rotation systems, including automated systems,within the printing device, cartridge, printer servicing station, and/ordocking station.

Without being limited by theory, it is believed that the cosmetic inkcomposition can be stabilized using a (meth)acrylic acid homopolymer ora salt thereof to minimize and/or prevent particle agglomeration and arheology modifier to introduce a secondary structure and build viscosityto suspend the particles in a weak colloidal gel. The colloidal gel canbe strong enough to hold the particles in suspension when not printing(thus inhibiting particle settling), but weak enough to break up duringprinting.

In particular, it was found that a cosmetic ink composition comprising aparticulate material, such as TiO₂, a rheology modifier selected fromthe group consisting of alkali swellable emulsion (“ASE”) polymers,hydrophobically modified alkali swellable emulsion (“HASE”) polymers,and combinations thereof, and a (meth)acrylic acid homopolymer or a saltthereof can be stable, yet still jettable using standard cartridges andnozzles in a thermal and/or piezo printer.

It was found that the cosmetic ink composition described herein can havea first dynamic viscosity at a shear rate of 0.1 sec⁻¹ measured at 25°C. of greater than about 1,100 cP, which can prevent settling of theparticles. It was further found that the cosmetic ink composition canhave a second dynamic viscosity at a shear rate of 1,000 sec⁻¹ measuredat 25° C. of less than about 100 cP, which can prevent clogging andspeed of flow issues through the cartridge and/or nozzles. Without beinglimited by theory, it is believed that a shear rate of 0.1 sec⁻¹ can berepresentative of storage conditions, while a shear rate of 1,000 sec⁻¹can be representative of printing conditions.

In one aspect, the cosmetic ink composition need not be agitated orshaken to re-disperse the particles before and/or during use because theparticles can remain in suspension over the shelf-life of the product.

Cosmetic Ink Composition

In one aspect, the cosmetic ink composition can be a skin carecomposition. The cosmetic ink composition can hide or camouflage a skinimperfection, such as hyperpigmentation, when deposited precisely andsubstantially only onto the skin imperfection.

The cosmetic ink composition can be non-Newtonian, meaning the cosmeticink composition can have a shear dependent viscosity and/or viscoelasticproperties. The cosmetic ink composition can show shear thinning effectsunder the fluid ejection conditions in which the ink is moved betweenthe cartridge and the printhead of an inkjet device. When the cosmeticink composition is jetted, the shear rate can increase, resulting in adecrease in the viscosity. Thus, the cosmetic ink composition can bestored without particle settling, yet the viscosity and particle sizeare such that the cosmetic ink composition can still be printed.

The cosmetic ink composition can comprise a particulate material, a(meth)acrylic acid homopolymer or a salt thereof, and a rheologymodifier.

In one aspect, the particulate material can be hydrophilic. In oneaspect, the particulate material can be substantially coated with one ormore ingredients to cause the particulate material to become morehydrophilic. As used herein, “substantially coated” can mean at leastabout 25%, preferably greater than about 50% surface coverage of theparticulate material, more preferably greater than about 75%, mostpreferably greater than about 90%. Suitable coating ingredients that canrender the particulate material hydrophilic in nature can includesilica, alumina, polyethylene glycol (PEG) 12 dimethicone, phytic acid,sodium glycerophosphate, and combinations thereof. The particulatematerial can be substantially coated with one or more coatingingredients using techniques known in the art. One advantage to using ahydrophilic particulate material is that hydrophilic particulatematerial can be more easily dispersed in water. In one aspect, theparticulate material can be titanium and/or iron oxide which has beensubstantially coated with silica and/or alumina.

Suitable particulate materials can include pigments; encapsulatedpigments; mica; clay; mixed metal oxide pigments; metal oxides such asiron oxide, titanium dioxide, zinc oxide, aluminum hydroxide, ironoxide, and combinations thereof; boron nitride; silica; talc; basic leadcarbonate; magnesium silicate; baryte (BaSO₄); calcium carbonate;pearlescent; colorants, including natural colorants and syntheticmonomeric and polymeric colorants; dyes such as azo, indigoid,triphenylmethane, anthraquinone, and xanthine dyes which are designatedas D&C and FD&C blues, browns, greens, oranges, reds, yellows, etc.;insoluble metallic salts of certified color additives, referred to asthe Lakes; and combinations thereof.

In one aspect, the particulate material can comprise titanium dioxide,iron oxide, and combinations thereof. In one aspect, the titaniumdioxide and/or iron oxide can be readily dispersed in water. In oneaspect, the titanium dioxide and/or iron oxide is not hydrophobicallytreated before use in the cosmetic ink composition because it may not bereadily dispersed in water. Suitable particulate material can includeslurries of titanium dioxide and iron oxide available from KOBO ProductsInc (South Plainfield, N.J.), or equivalents.

In one aspect, the cosmetic ink composition comprises a white pigment.

In one aspect, the cosmetic ink composition can have a white appearance.Alternatively, the cosmetic ink composition can have a white appearancewith tints of red and/or yellow.

Typical levels of particulate material for sufficient opacity to hideand/or camouflage skin imperfections can be around 30 active wt %. Inone aspect, the cosmetic ink composition can comprise greater than about15 active wt % particulate material, alternatively greater than about 20active wt %, alternatively greater than about 30 active wt %. In oneaspect, the cosmetic ink composition can comprise from about 1 to about30 active wt % particulate material, alternatively from about 3 to about25 active wt %, alternatively from about 5 to about 20 active wt %,alternatively from about 8 to about 18 active wt %.

The particulate material can comprise particles having a Particle SizeDistribution (PSD) D50 of about 100 nm to about 2,000 nm, alternativelyfrom about 150 nm to about 1,000 nm, alternatively from about 200 nm toabout 450 nm, alternatively from about 200 nm to about 350 nm. In oneaspect, the particulate material can comprise particles having a PSD D90of less than about 2 μm, alternatively less than about 1 μm. In oneaspect, the particulate material can comprise particles having a PSD D90of from about 700 to about 900 μm. Without being limited by theory, itis believed that if the particles are too big, they can clog themicrofluidic channels of the cartridge and disrupt printing. One skilledin the art would understand that an acceptable particle size can varydepending on printhead die architecture. In one aspect, the particulatematerial can comprise any PSD so long as the particles can move throughthe microfluidic channels of the cartridge and/or the printhead withoutcausing clogging. The Particle Size Distribution can be measuredaccording to the Particle Size Distribution Method described hereafter.

The particulate material can have a refractive index of between about1.1 and about 5.0, alternatively from about 1.5 to about 4,alternatively from about 2 to about 3.

The particulate material can have a density range of from about 1.5 toabout 6 g/mL, alternatively from about 2 to about 4 g/mL.

The cosmetic ink composition can comprise a rheology modifier. Rheologymodifiers can assist in preventing settling by keeping the particlesuniformly suspended such that little to no agitation of the cosmetic inkcomposition is needed.

One preferred group of rheology modifiers are ASE polymers. ASE polymerscontain a balance of hydrophilic (meth)acrylic acid monomers andhydrophobic (meth)acrylate ester monomers and can be supplied at highvolume solids in liquid form. ASE polymers rely on a change from low tohigh pH (neutralization) to trigger thickening. The “trigger” is builtinto the polymer by creating an approximately 50:50 ratio of(meth)acrylic acid, which is soluble in water, and a (meth)acrylateester, which is not soluble in water. When the acid is un-neutralized(low pH), the polymer is insoluble in water and does not thicken. Whenthe acid is fully neutralized (high pH), the polymer becomes soluble andthickens. ASE polymers are supplied at low pH (<5) and maintain a lowas-supplied viscosity (<100 cP) at solids of up to 35%. When subject toa pH of about 7 or higher, ASE polymers solubilize, swell, and thickenthe composition through volume exclusion. The degree of thickening canbe related to the molecular weight of the polymer. Because theirperformance depends on water absorption and swelling, ASE polymers tendto be very high in molecular weight, which allows them to thickenefficiently. The rheology profiles ASE polymers create are typicallysteeply shear-thinning (pseudoplastic), and thus ASE polymers are wellsuited to build high viscosity at very low shear rates. Differentrheological characteristics can be achieved by manipulating themolecular weight, as well as the types and amounts of acid and estermonomers, of the polymer.

In one aspect, the hydrophilic monomers of the ASE polymer can include(meth)acrylic acid and maleic acid. In one aspect, the hydrophobicmonomers of the ASE polymer can include the esters of (meth)acrylic acidwith C₁- to C₄-alcohols, in particular ethyl acrylate, butyl acrylate,and methyl methacrylate.

In one aspect, the ASE polymer can be synthesized from 10-90 wt % ofHydrophilic Monomer A and 10-90 wt % of Hydrophobic Monomer B. Thestructure of Hydrophilic Monomer A and Hydrophobic Monomer B are shownbelow.

wherein R₁ and R₂ are independently hydrogen or methyl;wherein R₃ is C₁ to C₄ alkyl.

Yet another group of rheology modifier suitable for use in the cosmeticink composition described herein are HASE polymers. These are tertiarypolymers that build on the ASE polymer chemistry by adding a hydrophobicacrylic ester and/or vinyl ester monomer to the polymer composition.HASE polymers retain the pH dependent behavior of their ASEcounterparts, but in addition to absorbing water, HASE polymers alsothicken via hydrophobe association. This mechanism, known as associativethickening (i.e. associating with any hydrophobic moiety in thecomposition), offers performance properties over a wider range of shearlevels and enables a wider range of rheology profiles than is possiblewith volume exclusion thickeners such as ASE and cellulosiccompositions.

The hydrophilic and hydrophobic monomers of the HASE polymers can be thesame as described with respect to the ASE polymers. The associativemonomer of the HASE polymer can be a monomer that shows a stronghydrophobic character. A preferred associative monomer is ester of(meth)acrylic acid with C₈-C₂₂ alcohols.

In one aspect, the HASE polymer can be synthesized from 10-90 wt %Hydrophilic Monomer A, 10-90 wt % Hydrophobic Monomer B, and 0.01 to 2wt % Associative Monomer C. The structure of Associate Monomer C isshown below.

wherein R₄ is hydrogen or methyl;wherein R₅ is C₈ to C₂₂ alkyl;wherein n is an integer from 0 to 50.

Alternatively, the HASE polymer can be synthesized from 10-90 wt %Hydrophilic Monomer A, 10-90 wt % Hydrophobic Monomer B, and 0.01 to 2wt % Associative Monomer D. The structure of Associative Monomer D isshown below.

wherein R₆ is hydrogen or methyl;wherein R₇ is C₈ to C₂₂ alkyl.

In one aspect, the associative monomer can be selected from the groupconsisting of steareth-20 methacrylate, beheneth-25 methacrylate, vinylneodecanoate, and combinations thereof. In one aspect, more than oneassociative monomers can be used in the synthesis of the HASE polymer.

In one aspect, ASE and HASE polymers can comprise a cross-linking agent.The cross-linking agent can contain at least two ethylenicallyunsaturated moieties, alternatively at least three ethylenicallyunsaturated moieties. Suitable cross-linking agents can include divinylbenzene, tetra allyl ammonium chloride, allyl acrylates, methacrylates,diacrylates, dimethacrylates of glycols and polyglycols, butadiene,1,7-octadiene, allyl-acrylamides, allyl-methacrylamides,bisacrylamidoacetic acid, N,N′-methylene-bisacrylamide, polyolpolyallylethers such as polyallylsaccharose and pentaerythroltriallylether, and mixtures thereof.

In one aspect, the cross-linking agent can be present at a level of fromabout 25 to about 5,000 ppm, alternatively from about 50 to about 1,000ppm, alternatively from about 100 to about 500 ppm.

Another group of rheology modifiers are hydrophobically-modifiedethylene oxide-based urethane (HEUR) polymers. Unlike ASE or HASE-typerheology modifiers, HEUR polymers are non-ionic and soluble at any pH.This solubility is due to the polymer's ethylene oxide backbone, whichis water soluble and makes up the majority of the polymer structure.Thus, HEUR polymers require a hydrophobic moiety in the composition tointeract with the ethylene oxide backbone to impart structure. Thecosmetic ink composition can comprise a HEUR polymer. Alternatively, thecosmetic ink composition comprises little to no hydrophobic moieties anddoes not comprise a HEUR polymer.

The rheology modifier can be a (meth)acrylate polymer, a (meth)acrylatecopolymer, and mixtures thereof. The rheology modifier can be selectedfrom the group consisting of ASE polymers, HASE polymers, andcombinations thereof. Suitable HASE polymers can include ACULYN™ Excel;ACRYSOL™ TT615; ACULYN™ 22; ACULYN™ 88; (all available from The DOWChemical Company, Lake Zurich, Ill.); and combinations thereof. SuitableASE polymers can include Rheovis® 1125 (available from BASF Corporation,Charlotte, N.C.), ACULYN™ 33; ACULYN™ 38 (both available from The DOWChemical Company, Lake Zurich, Ill.); and combinations thereof. Thecosmetic ink composition can comprise an ASE polymer. Alternatively, thecosmetic ink composition can comprise an HASE polymer.

The rheology modifier does not consist of a surfactant, an amine oxide,and/or a cellulosic ether.

The cosmetic ink composition can comprise any amount of rheologymodifier so long as the first dynamic viscosity of the cosmetic inkcomposition is greater than about 1,100 cP at a shear rate of 0.1 sec⁻¹measured at 25° C. The cosmetic ink composition can comprise greaterthan about 0.30 active wt % rheology modifier, alternatively greaterthan about 0.40 active wt %, alternatively greater than about 0.50active wt %. The cosmetic ink composition can comprise from about 0.30to about 1 active wt % rheology modifier, alternatively from about 0.30to about 0.80 active wt %, alternatively from about 0.40 to about 0.50active wt %. Active wt % can be measured using standard High PerformanceLiquid Chromatography-Mass Spectrometry (HPLC-MS) techniques. Oneadvantage to keeping the level of rheology modifier within this range isthat the viscosity of the cosmetic ink composition can be built suchthat the particles can be suspended in the composition. The particlescan be suspended for about 11 days or more at 25° C., alternativelyabout 30 days or more at 25° C., alternatively for about 90 days or moreat 25° C., alternatively for about 300 days or more at 25° C. Withoutbeing limited by theory, it is believed that at levels of rheologymodifier below this range the particles may not be sufficientlysuspended and settling may occur. If the level of rheology modifier istoo high, the viscosity of the cosmetic ink composition may increase toa point that can impact jetting (i.e. the cosmetic ink composition maynot shear thin enough for efficient printing).

In one aspect, the cosmetic ink composition can be substantially free ofneutral inorganic salts (as compared to an alkali salt base, like NaOH).Without being limited by theory, it is believed that neutral inorganicsalts, such as calcium chloride or sodium chloride, can increase theionic strength of the cosmetic ink composition and can disrupt theinternal structure, thus impacting stability. It is known that HASEand/or ASE polymers become polyelectrolytes at high pHs. As pHincreases, the carboxylic acids on the HASE and/or ASE polymers can beneutralized, generating ionic groups on the polymer chains that canproduce electrostatic repulsion. These electrostatic repulsions cancause the polymer to expand and form an internal structure in thecomposition. It is believed that inorganic neutral salts can shield thiselectrostatic repulsion and can cause the HASE and/or ASE polymer tochange structure, and thus its effectiveness in promoting stability.

The cosmetic ink composition can comprise a (meth)acrylic acidhomopolymer or a salt thereof. Non-limiting examples of acceptable saltscan include sodium, potassium, ammonium, and mixtures thereof. The(meth)acrylic acid homopolymer or salt thereof can be a low molecularweight material that can act to control particle size and can helpmaintain a low viscosity in the cosmetic ink composition. The(meth)acrylic acid homopolymer or salt thereof does not greatly increaseviscosity of the cosmetic ink composition. Non-limiting examples ofsuitable (meth)acrylic acid homopolymers or salt thereof can includesodium polyacrylate such as Darvan® 811D (available from RT VanderbiltHolding Company Inc., Norwalk, Conn.), ammonium polyacrylate having aweight average molecular weight of about 3,500 daltons such as Darvan®821A (available from RT Vanderbilt Holding Company Inc.), andcombinations thereof. The (meth)acrylic acid homopolymer or salt thereofhave a weight average molecular weight of less than about 20,000daltons, preferably less than about 10,000 daltons, more preferably lessthan about 5,000 daltons. The cosmetic ink composition can comprise a(meth)acrylic acid homopolymer or salt thereof having a weight averagemolecular weight of from about 1,000 to about 20,000 daltons,alternatively from about 1,000 to about 10,000 daltons, alternativelyfrom about 2,000 to about 5,000 daltons, alternatively from about 2,500to about 4,000 daltons. Weight average molecular weight can be measuredby standard High Performance Size-Exclusion Chromatography per ASTMmethod D5296-11 (Sep. 1, 2011).

In one aspect, the (meth)acrylic acid homopolymer or salt thereof is nota film forming polymer. Without being limited by theory it is believedthat the (meth)acrylic acid homopolymer or salt thereof will not form afilm because of the low molecular weight.

The cosmetic ink composition can comprise from about 0.01 to about 1active wt % (meth)acrylic acid homopolymer or salt thereof,alternatively from about 0.10 to about 0.85 active wt %, alternativelyfrom about 0.20 to about 0.75 active wt %, alternatively about 0.30 toabout 0.65 active wt %. Without being limited by theory, it is believedthat the (meth)acrylic acid homopolymer or salt thereof can controlagglomeration, and thus the particle size, of the particulate materialby creating a negative surface charge around the particles. Thus, the(meth)acrylic acid homopolymer or salt thereof can help to maintain aparticle size that is compatible with printer cartridges and nozzles.Without being limited by theory, it is believed that a cosmetic inkcomposition comprising below 0.01 active wt % (meth)acrylic acidhomopolymer or salt thereof may not have sufficient particle sizecontrol and/or the viscoelastic modulus may be too high to allow forreliable refill of the microfluidics.

The ratio of the (meth)acrylic acid homopolymer or salt thereof to therheology modifier can be less than about 1. The ratio of (meth)acrylicacid homopolymer or salt thereof to rheology modifier can be from about0.10 to about 0.75, alternatively from about 0.30 to about 0.65. Withoutbeing limited by theory it is believed that if the level of(meth)acrylic acid homopolymer or salt thereof is greater than the levelof rheology modifier, the rheology modifier may not be able to build theinternal structure needed to suspend the particles. If the ratio of(meth)acrylic acid homopolymer or salt thereof to rheology modifier istoo low, agglomeration may not be well controlled and the particle sizemay become too large to fit through printer nozzles, making printingdifficult.

It is believed that stability is inversely proportional to the level of(meth)acrylic acid homopolymer or salt thereof and directly proportionalto the level of rheology modifier.

The cosmetic ink composition can have a first dynamic viscosity ofgreater than about 1,100 cP at a shear rate of 0.1 sec⁻¹ measured at 25°C. and a second dynamic viscosity of less than about 100 cP at a shearrate of 1,000 sec⁻¹ measured at 25° C. The cosmetic ink composition canhave a first dynamic viscosity of from about 1,100 cP to about 10,000 cPat a shear rate of 0.1 sec⁻¹ at 25° C., alternatively from about 1,500cP to about 8,000 cP, alternatively from about 2,000 cP to about 5,000cP. The cosmetic ink composition can have a second dynamic viscosity offrom about 10 cP to about 100 cP at a shear rate of 1,000 sec⁻¹ at 25°C., alternatively from about 20 to about 80 cP. Viscosity can bemeasured according to the Viscosity Test Method described hereinafter.One advantage to having a first and second dynamic viscosity in thisrange is that at high shear rate, the cosmetic ink composition can dropto a viscosity that is similar to Newtonian inks, yet can still maintaina viscosity sufficient to suspend the particles when not printing.

The cosmetic ink composition can have a first dynamic viscosity measuredat a shear rate of 0.1 sec⁻¹ at 25° C. that is about 70% higher than thesecond dynamic viscosity of the cosmetic ink composition when measuredat a shear rate of 1,000 sec⁻¹ at 25° C., alternatively about 80%higher, alternatively about 90% higher, alternatively about 95% higher.The cosmetic ink composition can have a first dynamic viscosity measuredat a shear rate of 0.1 sec⁻¹ at 25° C. that is about 25 times greaterthan the second dynamic viscosity of the cosmetic ink composition whenmeasured at a shear rate of 1,000 sec⁻¹ at 25° C., alternatively about35 times greater, alternatively about 50 times greater, alternativelyabout 80 times greater.

The cosmetic ink composition can have temperature dependent viscosity.Lower viscosity was observed at a shear rate of 1000 sec⁻¹ at anelevated temperature of about 70° C. The cosmetic ink composition canhave a storage modulus (G′) of from about 2 to about 10, alternativelyfrom about 3 to about 8, alternatively from about 4 to about 6. Withoutbeing limited by theory, it is believed that if the G′ of the cosmeticink composition is greater than about 10, the decap or start up afteridle time in the printhead may be difficult without intervention becausethe composition is too elastic. Storage modulus can be measuredaccording to the Oscillatory Strain Sweep Method described hereafter.

The cosmetic ink composition can have a loss modulus (G″) of from about1 to about 5, alternatively from about 1.5 to about 4, alternativelyfrom about 2 to about 3. Loss modulus can be measured according to theOscillatory Strain Sweep Method described hereafter.

The ratio of loss modulus to storage modulus, or tan(delta), is a usefulrepresentation of the extent of elasticity in a fluid. In this case, itcan be a measure of the intrinsic stability of the cosmetic inkcomposition. When G″ is higher than G′, tan(delta) is greater than about1 and indicates a viscous dominant fluid behavior. When G′ is higherthan G″, tan(delta) is less than about 1 and indicates an elasticdominant fluid behavior.

The cosmetic ink composition can have a tan(delta) of about 1.Alternatively, the cosmetic ink composition can have a tan(delta) ofless than about 1, alternatively less than about 0.6. Without beinglimited by theory it is believed that when the tan(delta) is less thanabout 0.6, particle settling can be minimized and/or prevented. Thecosmetic ink composition can have a tan(delta) of from about 0.2 toabout 1, alternatively from about 0.4 to about 0.9, alternatively fromabout 0.6 to about 0.8.

The cosmetic ink composition can have a zeta potential of about negative20 or less, alternatively about negative 30 or less, alternativelygreater than about positive 20, alternatively greater than aboutpositive 30. The cosmetic ink composition can have a zeta potential ofabout negative 20 or less, or greater than about positive 20. Oneadvantage to having a zeta potential in this range is that the surfacecharge of the particles can be increased, thus preventing agglomerationof the particles. Zeta potential can be measured according to the ZetaPotential Test Method described hereafter.

The cosmetic ink composition can have a neat pH of greater than about7.5. The cosmetic ink composition can have a neat pH of about 7.5 toabout 9.0, alternatively from about 7.5 to about 8.5. Without beinglimited by theory, it is believed that at a pH lower than about 7.5,syneresis can occur at a faster rate. It is believed that at a lower pH,the equilibrium between the carboxylic acid and carboxylate salts of therheology modifier can be pushed toward the protonated acid and thereforeare not available to suspend the particles. It is believed that as thepH increases, the larger the negative zeta potential becomes, thuspreventing agglomeration of the particles. The cosmetic ink compositioncan comprise a buffering agent for adjusting the pH conditions. Thebuffering agent can be any basic excipient. In one aspect, the bufferingagent can be a strong base, such as sodium hydroxide, potassiumhydroxide, calcium hydroxide, and mixtures thereof. The neat pH of thecosmetic ink composition can be measured by standard methodology knownto those skilled in the art.

The cosmetic ink composition can have a surface tension of from about 25to about 60 dyn/cm, alternatively from about 30 to about 55 dyn/cm,alternatively from about 40 to about 50 dyn/cm.

The cosmetic ink composition can have an opacity of at least 0.2. In oneaspect, the cosmetic ink composition can comprise an opacity of fromabout 0.2 to about 1, alternatively from about 0.25 to about 0.8,alternatively from about 0.3 to about 0.5.

The cosmetic ink composition can be substantially free of particlesettling. Substantially free of particle settling can mean that thevariation between the weight % solids of the top and bottom of a sampleof the cosmetic ink composition is less than 5% at ambient conditions at4 days after formulation, alternatively less than about 3%,alternatively less than about 1%. Particle settling can be measuredaccording to the Particle Settling Test Method described hereafter.

The cosmetic ink composition can be substantially free of particleagglomeration. Substantially free of particle agglomeration can meanthat the cosmetic ink composition exhibits less than about 25 nm ofparticle growth per month at ambient conditions, alternatively less thanabout 15 nm, alternatively less than about 10 nm. The rate ofagglomeration can be determined by measuring particle size according tothe Particle Size Distribution method described hereafter over a periodof time.

The cosmetic ink composition can have less than about 10% separation at11 days after formulation at 25° C., alternatively less than about 5%,alternatively less than about 2%, alternatively less than about 1%. Inone aspect, the cosmetic ink composition can have less than about 4 mmof separation at 11 days after formulation at 25° C., alternatively lessthan about 2 mm, alternatively less than about 1 mm, alternatively lessthan about 0.50 mm. Separation can be measured according to theSeparation Test Method described hereafter.

The cosmetic ink composition can have a shelf-life of about 1 month,alternatively about 3 months, alternatively about 6 months,alternatively about 12 months, alternatively about 18 months,alternatively about 24 months. As used herein, “shelf-life” means theamount of time the particles can remain uniformly suspended in thecosmetic ink composition at ambient conditions without the need forshaking or agitation.

The cosmetic ink compositions may further comprise a humectant as acarrier or chassis for the other components in the cosmetic inkcomposition. An exemplary class of humectants can include polyhydricalcohols. Suitable polyhydric alcohols can include polyalkylene glycolsand alkylene polyols and their derivatives, including propylene glycol,dipropylene glycol, polypropylene glycol, polyethylene glycol andderivatives thereof; sorbitol; hydroxypropyl sorbitol; erythritol;threitol; pentaerythritol; xylitol; glucitol; mannitol; butylene glycol(e.g., 1,3-butylene glycol); pentylene glycol; hexane triol (e.g.,1,2,6-hexanetriol); glycerin; ethoxylated glycerine; propoxylatedglycerine; and mixtures thereof.

Other suitable humectants can include sodium2-pyrrolidone-5-carboxylate; guanidine; glycolic acid and glycolatesalts (e.g., ammonium and quaternary alkyl ammonium); lactic acid andlactate salts (e.g., ammonium and quaternary alkyl ammonium); aloe verain any of its variety of forms (e.g., aloe vera gel); hyaluronic acidand derivatives thereof (e.g., salt derivatives such as sodiumhyaluronate); lactamide monoethanolamine; acetamide monoethanolamine;urea; sodium pyroglutamate, water-soluble glyceryl poly(meth)acrylatelubricants (such as Hispagel®, available from BASF, Ludwigshafen,Germany); and mixtures thereof.

The cosmetic ink composition can comprise from about 1 to about 40active wt % humectant, alternatively from about 5% to about 35%,alternatively from about 10% to about 30%, alternatively from about 15%to about 20%. Alternatively, the cosmetic ink composition can comprisefrom about 20 to about 30 active wt % humectant.

Without being limited by theory, it is believed that at a level of about20 active wt % or more the humectant can help prevent drying and/orclogging of the nozzles and/or cartridge when the cosmetic inkcomposition is not being printed.

In one aspect, the level of humectant is less than about 30 active wt %to promote fast dry times of the cosmetic ink composition on the skin.

The cosmetic ink composition can be delivered alone or in the presenceof a dermatologically-acceptable carrier. The phrase“dermatologically-acceptable carrier”, as used herein, means that thecarrier is suitable for topical application to a keratinous tissue, hasgood aesthetic properties, is compatible with any additional componentsof the cosmetic ink composition, and/or will not cause any untowardsafety or toxicity concerns. In one aspect, the cosmetic ink compositionis safe for use on skin. In one aspect, the cosmetic ink compositiondoes not comprise alkyds, celluloses, formaldehydes, phenolics, ketones,rubber resins, and combinations thereof because such ingredients may notbe compatible with use on human skin. In one aspect, the cosmetic inkcomposition can be hypoallergenic. Water is by far the most commoncarrier, and is typically used in combination with other carriers. Thecarrier can be in a wide variety of forms. Non-limiting examples includesimple solutions (water or oil based) or emulsions. The dermatologicallyacceptable carrier can be in the form of an emulsion. Emulsion may begenerally classified as having a continuous aqueous phase (e.g.,oil-in-water and water-in-oil-in-water) or a continuous oil phase (e.g.,water-in-oil and oil-in-water-in-oil). The oil phase may comprisesilicone oils, non-silicone oils such as hydrocarbon oils, esters,ethers, and the like, and mixtures thereof. For example, emulsioncarriers can include, but are not limited to, continuous water phaseemulsions such as silicone-in-water, oil-in-water, andwater-in-oil-in-water emulsion and continuous oil phase emulsions suchas water-in-oil and water-in-silicone emulsions, andoil-in-water-in-silicone emulsions.

The cosmetic ink composition can comprise water, preferably deionizedwater. The cosmetic ink composition can comprise from about 40% to about75% water, by weight of the cosmetic ink composition, alternatively fromabout 55% to about 70%, alternatively from about 60% to about 68%.

Additionally, the cosmetic ink composition can optionally includeanti-fungal and/or anti-bacterial components. Examples of anti-fungaland/or anti-bacterial components can include isothiazolinone such asmethylisothiazolinone and methylchloroisothiazolinone.

The cosmetic ink composition can optionally comprise a preservative.Non-limiting examples of suitable preservatives can include phenoxyethanol, 1,2-Hexanediol, 1,2-Octanediol (commercially available asSymDiol® 68 from Symrise, AG, Branchburg, N.J.), farnesol, 2-methyl5-cyclohexypentanol, 1,2-decanediol, and combinations thereof. Thecosmetic ink composition can comprise from about 0.01% to about 10%preservative, alternatively from about 0.1% to about 5%, alternativelyfrom about 1% to about 3%, all by weight of the cosmetic inkcomposition. One advantage to including a preservative is that it canhelp to prevent microbial growth in the cosmetic ink composition, forinstance if the cosmetic ink composition becomes contaminated withbacteria from the skin.

The cosmetic ink composition may comprise a monohydric alcohol. Thecosmetic ink composition can comprise about 50 ppm or more of amonohydric alcohol. The cosmetic ink composition can comprise from about50 to about 10,000 ppm of a monohydric alcohol, alternatively from about100 to about 5,000 ppm, alternatively from about 100 to about 1,000 ppm.Suitable monohydric alcohols include methanol, ethanol, 1-propanol,2-propanol, 1-butanol, 2-butanol, 2-methyl-1-propanol and2-methyl-2-propanol.

The cosmetic ink composition may comprise a safe and effective amount ofone or more skin care actives (“active”) useful for regulating and/orimproving the skin. “Safe and effective amount” means an amount of acompound or composition sufficient to induce a positive benefit but lowenough to avoid serious side effects (i.e., provides a reasonablebenefit to risk ratio within the judgment of a skilled artisan). A safeand effective amount of an active can be from about 1×10⁻⁶ to about 25%,alternatively from about 0.0001 to about 20%, alternatively from about0.01 to about 10%, alternatively from about 0.1 to about 5%,alternatively from about 0.2 to about 2%, all by weight of the cosmeticink composition.

Suitable skin care actives include, but are not limited to, vitamins(e.g., B3 compounds such as niacinamide, niacinnicotinic acid, andtocopheryl nicotinate; B5 compounds such as panthenol; vitamin Acompounds and natural and/or synthetic analogs of Vitamin A, includingretinoids, retinol, retinyl acetate, retinyl palmitate, retinoic acid,retinaldehyde, retinyl propionate, and carotenoids (pro-vitamin A);vitamin E compounds, or tocopherol, including tocopherol sorbate andtocopherol acetate; vitamin C compounds, including ascorbate, ascorbylesters of fatty acids, and ascorbic acid derivatives such as magnesiumascorbyl phosphate and sodium ascorbyl phosphate; ascorbyl glucoside;and ascorbyl sorbate); peptides (e.g., peptides containing ten or feweramino acids, their derivatives, isomers, and complexes with otherspecies such as metal ions); sugar amines (e.g., N-acetyl-glucosamine);sunscreens; oil control agents; tanning actives; anti-acne actives;desquamation actives; anti-cellulite actives; chelating agents; skinlightening agents; flavonoids; protease inhibitors (e.g., hexamidine andderivatives); non-vitamin antioxidants and radical scavengers; salicylicacid; hair growth regulators; anti-wrinkle actives; anti-atrophyactives; minerals; phytosterols and/or plant hormones; tyrosinaseinhibitors; N-acyl amino acid compounds; inositol; undecylenoylphenylalanine; moisturizers; plant extracts; and derivatives of any ofthe aforementioned actives; and combinations thereof. The term“derivative” as used herein refers to structures which are not shown butwhich one skilled in the art would understand are variations of thebasic compound. For example, removing a hydrogen atom from benzene andreplacing it with a methyl group.

In one aspect, the cosmetic ink composition can comprise peroxide,including hydrogen peroxide and/or benzoyl peroxide.

In one aspect, the cosmetic ink composition can comprise a skin careactive selected from the group consisting of niacinamide; inositol;undecylenoyl phenylalanine; and combinations thereof.

In one aspect, the cosmetic ink composition is substantially free oflatex polymer binders and/or a film forming polymers. In one aspect, thecosmetic ink composition comprises less than about 10% latex polymerbinders and/or film forming polymers, alternatively less than about 1%,alternatively less than about 0.1%. Without being limited by theory, itis believed that latex polymer binders and/or film forming polymers canmake printing can be difficult because these polymers can solidify afterevaporation and irreversibly plug the nozzles.

In one aspect, the cosmetic ink composition comprises from about 10% toabout 30% solids. In one aspect, the cosmetic ink composition comprisesless than 40% solids. Without being limited by theory, it is believedthat at a solids level of greater than 40%, such as in prepaints orpaints, printing can be difficult because a high level of solids maylead to irreversible nozzle clogging.

In one aspect, the cosmetic ink composition can be removeable withwater, alternatively with soap and water.

Personal Care Device

In one aspect, the cosmetic ink composition described herein can beapplied to the skin using a hand-held personal care device. The personalcare device can analyze the skin, identify skin imperfections, anddeposit the cosmetic ink composition onto the identified skinimperfection in order to hide and/or camouflage the skin imperfection.An exemplary personal care device is described in U.S. Pat. No.9,522,101.

In one aspect, the personal care device can comprise a sensor configuredto take at least one image of skin and a processor configured tocalculate the average background lightness value of the image on a greyscale (lightness value on a grey scale is herein referred to as “Lvalue”). Further, from the same image, a local L value can be calculatedfor individual pixels or a group of pixels. The processor can thencompare the local L value to the background L value to identify skinimperfections. When a skin imperfection is identified, the processor canactivate one or more nozzles to fire and dispense the cosmetic inkcomposition onto the skin imperfection.

A skin imperfection is an area of skin where the absolute value of thedifference between a local L value and the background L, this differencebeing defined as the measured delta L (“ΔL_(M)”), is greater than apredetermined set delta L (“ΔL_(S)”). The background L can be preset orcalculated anywhere within the image. The image can be taken where thenozzles will fire the cosmetic ink composition. The background L can bethe arithmetic average, median, or mean of a plurality of local Ls,which means the calculation can include all of the local Ls in theimage, or a subset thereof.

FIG. 1, shows an exploded view of personal care device 40. Physicalspacer 42 of personal care device 40 is directly above skin surface 18.Physical spacer 42 has a set, predetermined height a such that when itcontacts skin surface 18, the mechanical and electrical elements are allat a known distance from skin surface 18. In one aspect, the height a isfrom about 1 mm to about 20 mm, alternatively from about 3 mm to about15 mm, alternatively from about 4 mm to about 10 mm.

The mechanical and electrical elements associated with personal caredevice 40 can include, but are not be limited to, light 44, sensor 46,nozzle array 20 which is embedded on cartridge die 57 which is attachedto cartridge 52. Cartridge die 57 can be made of silicon, glass,machinable glass ceramic, sapphire, alumina, printed wiring boardsubstrates (for example, Liquid Crystal Polymer, polyimide etc.) withinwhich nozzle array 20 can be formed. Nozzle array 20 can be in a linearconfiguration, multiple rows, off-set, sine wave, curved, circular, sawtooth arrangements, and combinations thereof. All of these elements canbe enclosed within optional apparatus housing 41.

Light 44 can illuminate the area of skin surface 18 within physicalspacer 42 such that sensor 46 has relatively constant illumination.Background lighting can affect sensor 46 as portions of physical spacer42 lift off skin surface 18 and allow background light in and theillumination from light 44 to escape. Small deviations in illuminationcan be corrected for provided light 44 provides a relatively constantbackground illumination. In one aspect, physical spacer 42 can beopaque. Light 44 can be a LED, incandescent light, neon bulb based, orany other commercially available source of illumination. Light 44 canhave constant illumination or adjustable illumination. For example, anadjustable light source might be useful if the background illuminationis excessively bright or dark.

Sensor 46 can be any component that is capable of obtaining a visualproperty of an area of skin surface. Non-limiting examples of sensorscan include optical sensors, image capture devices, spectrophotometers,photonic measuring devices for wavelengths within the visible spectrumas well as those wavelengths above and below the visible spectrum whichcould measure sub-surface features, and combinations thereof. The imagecapture device can be any of a variety of commercially available devicessuch as a simple camera or a digital cmos camera chip. In one aspect,the image capture device can be a camera and the images can be taken orconverted to a standard grey scale that is known in the art. It isunderstood that any numerical scale that measures lightness to darknesscan be considered a “grey scale”. Moreover, as used herein, “grey scale”is intended to be a linear scale, or one band, or one visual attribute.For example, one “grey scale” visual attribute could be singlewavelength or a narrow wavelength to define a specific visual color.Another example of one “grey scale” visual attribute could be a mix ofwavelength numerical values averaged for each pixel making up the image,such as a true black, grey or white image from an RGB mixture.

Sensor 46 can take a measurement of the L value of skin surface 18and/or an image of skin surface 18 and can send it to processor 50 viaimage capture line 48 for analysis. The image may be analyzed for localL values, background L values, or both. Grey scale conversion can occurwithin the analytical processing capabilities of processor 50. Thecomparison of background L to local L to determine the ΔL_(M) occurswithin processor 50, which can be a commercially available programmablechip, or other commercially available processing units.

Processor 50 is generally referred to as a central processing unit(“CPU”). The CPU can be a single programmable chip like those found inconsumer electronic devices such as a laptop computer, a cell phone, anelectric razor, and the like. The CPU may comprise an ApplicationSpecific Integrated Circuit (ASIC), controller, Field Programmable GateArray (FPGA), integrated circuit, microcontroller, microprocessor,processor, and the like. The CPU may also comprise memory functionality,either internal to the CPU as cache memory, for example Random AccessMemory (RAM), Static Random Access Memory (SRAM), and the like, orexternal to the CPU, for example as Dynamic Random-Access Memory (DRAM),Read Only Memory (ROM), Static RAM, Flash Memory (e.g., Compact Flash orSmartMedia cards), disk drives, Solid State Disk Drives (SSD), orInternet Cloud storage. While it is anticipated that a remote CPU,either tethered to the personal care device or which communicateswirelessly, can be used, a local CPU within the personal care device isexemplified herein.

Images can be taken in sequence or preferably continuously. The imagecapture device can take images at a speed of at least 4 frames persecond, alternatively at least 100 frames per second, alternatively atleast 200 frames per second, alternatively at least 600 frames persecond.

The CPU can process at a rate of 100 frames per second, alternativelygreater than 200 frames per second, alternatively greater than 600frames per second.

The results of the image analysis, when compared to criteriapre-programmed into processor 50, may result in a desired treatment ofskin surface 18. For instance, when the calculated ΔL_(M) exceeds thepre-determined ΔL_(S), a signal is sent from processor 50 to cartridge52, via cartridge line 51, to fire one or more nozzles 21 in nozzlearray 20 and dispense the cosmetic ink composition.

Power for cartridge 52, light 44, sensor 46, processor 50, and othermechanical and electrical elements that might be present can be suppliedby power element 54 via one or more power lines 55.

Power element 54 can be turned off and on, which in turn turns personalcare device 40 off and on, via power switch 56 which can be locatedanywhere on personal care device 40, but is shown here on device cover58. Power element 54 may include energy storage functionality via abattery, a rechargeable battery, an electrochemical capacitor, adouble-layer capacitor, a supercapacitor, a hybrid battery-capacitorsystem, and combinations thereof.

FIG. 2 shows an exploded view of cartridge 52 comprising cartridge cap62 and cartridge body 64. Cartridge body 64 can include standpipe 66which is typically enclosed within cartridge body 64 and defines nozzleoutlet 68. Optional filter 70 can help keep excessively large particles,and other debris out of nozzle array 20. Filter 70 and nozzle array 20can be on opposite sides of nozzle outlet 68. Cosmetic ink composition74 can be contained within cartridge body 64. Foam core 72 can at leastpartially fill cartridge 64 and helps to regulate back pressure ofcosmetic ink composition 74. Back pressure can be regulated via bladders(not shown) and other methods known to the art. Foam core 72 shown hereis just one example of how to help regulate the flow of cosmetic inkcomposition 74 to standpipe 66 through filter 70 and into nozzle array20. Connector 78 can provide the electrical power and signal to nozzlearray 20. Cosmetic ink composition 74 may be ejected from the cartridge52 by piezoelectric means, thermal means, mechanical pumping means, or acombination of these.

An exemplary cartridge for use herein can include cartridges describedin Patent Application US 2002/0167566.

There is no technical difference between an image used for background Lvalues and those used for local L values, the difference is in theanalysis of the image. Hence, the images are continually sent to theprocessor to calculate the L values and ΔL_(M) values. By “sent” it isunderstood, that preferably at least 4 bits of data per pixel aretransferred for each image, and preferably, this 4-bit (or more) packetof data is used in the calculation of each local L value.

It is understood, that the background L can be calculated once in atreatment period and that value can be reused throughout the treatmentperiod. Alternatively, it can be continually recalculated as long as thetreatment process goes on. Moreover, there can be pre-programmedtriggers to initiate a recalculation of the background L. Also, thebackground L may be retrieved from the processor memory to be used forthe current background L.

When the ΔL_(M) exceeds the predetermined value, the cosmetic inkcomposition can be deposited onto at least a portion of the skinimperfection. In particular, the cosmetic ink composition can bedeposited via an array of nozzles and the local L can be calculatedalong the length of, and in the firing range of, the array of nozzles.An individual nozzle may be fired to deposit the cosmetic inkcomposition, or multiple nozzles can be fired at the same time. Thenumber of nozzles fired along the array of nozzles can be adjusted basedon the size of the ΔL_(M) and the size of the skin imperfection.Furthermore, the frequency of nozzle firing can be adjusted based on theALM, with more droplets being fired in succession in response to largerΔL_(M) values.

The personal care device may deposit the cosmetic ink composition indroplets having an average diameter of from about from about 0.1 μm toabout 60 μm, alternatively from about 1 μm to about 50 μm, alternativelyfrom about 5 μm to about 40 μm. Preferably, the cosmetic ink compositioncan be applied to the skin imperfection in a discontinuous pattern ofdiscrete droplets.

The cosmetic ink composition can be printed from a cartridge having amicro-electro-mechanical system (MEMS) that is different from typicalconsumer printing applications. It is known that the typical chamberheight and nozzle plate thicknesses are from about 25 to about 50 μmsince typical printing inks have a viscosity of less than about 10 cP.In one aspect, the cartridge can comprise a chamber height and nozzleplate thicknesses of from about 10 to about 20 μm, preferably from about12 to about 17 μm. Without being limited by theory it is believed thatthe shorter chamber height and plate thickness can help minimize viscousloss. In addition, most consumer printing applications are optimized forprinting at 10 kHz or more, so ink formulas and microfluidics aredesigned to achieve rapid refill. However, operating the cosmetic inkcomposition described herein at this frequency range can result instreaming and/or de-priming due to gulping of air.

The cosmetic ink composition can be printed using the following start-upsequence: heating the substrate to about 60° C. for less than about 600ms, firing the nozzles in a burst of from about 100 to about 500 firesat a frequency of about 300 to about 1000 Hz, and then maintaining thelow shear condition with continuous 4 Hz firing. While it is possiblethe nozzles will start up with different algorithms, it is likely thatthe cosmetic ink composition would not be transitioned from its viscousat-rest state to a flowing state.

Also described herein is a method for depositing the cosmetic inkcomposition onto skin. The method for depositing a cosmetic inkcomposition onto skin can comprise the steps of:

-   -   a. providing a personal care device comprising one or more        nozzles and a cartridge operatively associated with the one or        more nozzles, wherein a cosmetic ink composition is disposed        within the cartridge; and    -   b. depositing the cosmetic ink composition onto a portion of        skin, wherein the cosmetic ink composition is deposited in a        discontinuous droplet pattern.

More specifically, a method for depositing a cosmetic ink compositiononto skin can comprise the steps of:

-   -   a. providing a personal care device comprising an array of        nozzles;    -   b. providing a background lightness (L) value;    -   c. obtaining a treatment image of skin and calculating at least        one local L value of individual pixels or group of pixels within        the treatment image;    -   d. comparing the local L value to the background L value;    -   e. identifying a skin deviation where the absolute value of the        difference between the local L value and the background L value        is greater than a predetermined set delta L value; and treating        the skin deviation with a cosmetic ink composition;        wherein the ink composition comprises a particulate material        having a Particle Size Distribution D50 of about 100 nm to about        2,000 nm; a (meth)acrylic acid homopolymer or salt thereof        having a weight average molecular weight of less than about        20,000 daltons; and a rheology modifier, wherein the rheology        modifier is selected from the group consisting of alkali        swellable emulsion polymers, hydrophobically modified alkali        swellable emulsion polymers, and combinations thereof; and        wherein the ink composition has a first dynamic viscosity of        greater than about 1,100 cP at a shear rate of 0.1 sec⁻¹        measured at 25° C. and a second dynamic viscosity of less than        about 100 cP at a shear rate of 1,000 sec⁻¹ measured at 25° C.

EXAMPLES AND DATA

The following data and examples, including comparative examples, areprovided to help illustrate cosmetic ink compositions described herein.The exemplified compositions are given solely for the purpose ofillustration and are not to be construed as limitations of the presentinvention, as many variations thereof are possible without departingfrom the spirit and scope of the invention. All parts, percentages, andratios herein are by weight unless otherwise specified.

A series of formulas were prepared in a fractional factorial studydesign to understand the effect of the level of (meth)acrylic acidhomopolymer or salt thereof and rheology modifier in the formula.Examples 1-18 were made according to the procedure described hereafter.The level of Polyvinylpyrrolidone/vinyl acetate (PVP/VA) and 1,2Hexanediol/Caprylyl Glycol (commercially available as Symdiol® fromSymrise AG, Branchburg, N.J.) was kept constant at 1%, respectively. Thelevel of total particulate material, propylene glycol, (meth)acrylicacid homopolymer sodium polyacrylate (Darvan® 811D), and HASE typerheology modifier (ACULYN™ Excel, available from The Dow ChemicalCompany, Lake Zurich, Ill.) were varied. Example 4 is a controlcontaining no (meth)acrylic acid homopolymer or salt thereof.

The samples were stored in sealed glass jars at 50° C. untilmeasurements were performed. Samples were tested to determine theoptimal level of (meth)acrylic acid homopolymer or salt thereof andrheology modifier by measuring the amount of separation. The measurementof separation at 50° C. was used as a screening tool to understand whichformulas could build sufficient internal structure to suspend theparticles. Samples that exhibit a large change in particle sizedistribution and/or particle settling separation suggest that theformulations are unstable.

Examples 1-18 were made according to the following formulas. Weightpercent is shown as added.

TABLE 1 1 2 3 4 5 6 Phase Description Wt. % Wt. % Wt. % Wt. % Wt. % Wt.% A 75 wt % TiO₂ Slurry 12.18 12.18 12.18 12.18 18.81 5.55 (WPG75PFSP) ¹A 45 wt % Iron Oxide 1.78 1.78 1.78 1.78 2.76 0.81 Slurry (WPG45GYSP) ¹A 55 wt % Iron Oxide 0.11 0.11 0.11 0.11 0.17 0.05 Slurry (WPG55GRSP) ¹B Deionized Water 60.06 60.06 57.53 61.73 50.99 66.32 B PuraGuard ™20.00 20.00 20.00 20.00 20.00 20.00 Propylene Glycol² B 50 wt % PVP/VA1.00 1.00 1.00 1.00 1.00 1.00 735W³ in water B Symdiol ® 68⁴ 1.00 1.001.00 1.00 1.00 1.00 C 5 wt % Darvan ® 2.20 2.20 4.20 0.00 2.20 2.20811D⁵ in water D 15 wt % ACULYN ™ 1.67 1.67 2.20 2.20 3.07 3.07 Excel⁶in water 7 8 9 10 11 12 Phase Description Wt. % Wt. % Wt. % Wt. % Wt. %Wt. % A 75 wt % TiO₂ Slurry 15.58 15.58 8.79 8.79 8.45 8.45 (WPG75PFSP)¹ A 45 wt % Iron Oxide 2.28 2.28 1.29 1.29 1.24 1.24 Slurry (WPG45GYSP)¹ A 55 wt % Iron Oxide 0.14 0.14 0.08 0.08 0.07 0.07 Slurry (WPG55GRSP)¹ B Deionized Water 46.80 67.74 56.64 73.58 79.65 48.17 B PuraGuard ™29.47 10.53 29.47 10.53 3.46 36.54 Propylene Glycol² B 50 wt % PVP/VA1.00 1.00 1.00 1.00 1.00 1.00 735W³ in water B Symdiol ® 68⁴ 1.00 1.001.00 1.00 1.00 1.00 C 5 wt % Darvan ® 3.20 1.20 1.20 3.20 3.00 1.40811D⁵ in water D 15 wt % ACULYN ™ 0.53 0.53 0.53 0.53 2.13 2.13 Excel⁶in water 13 14 15 16 17 18 Phase Description Wt. % Wt. % Wt. % Wt. % Wt.% Wt. % A 75 wt % TiO₂ Slurry 21.95 21.95 2.41 2.41 15.91 15.91(WPG75PFSP) ¹ A 45 wt % Iron Oxide 3.22 3.22 0.35 0.35 2.33 2.33 Slurry(WPG45GYSP)¹ A 55 wt % Iron Oxide 0.20 0.20 0.02 0.02 0.14 0.14 Slurry(WPG55GRSP)¹ B Deionized Water 55.25 42.69 62.77 79.83 37.95 72.63 BPuraGuard ™ 12.72 27.28 27.78 12.72 36.54 3.46 Propylene Glycol² B 50 wt% PVP/VA 1.00 1.00 1.00 1.00 1.00 1.00 735W³ in water B Symdiol ® 68⁴1.00 1.00 1.00 1.00 1.00 1.00 C 5 wt % Darvan ® 3.20 1.20 3.20 1.20 3.001.40 811D⁵ in water D 15 wt % ACULYN ™ 1.47 1.47 1.47 1.47 2.13 2.13Excel⁶ in water ¹ Supplied by KOBO Products Inc (South Plainfield, NJ).²Available from The Dow Chemical Company (Lake Zurich, IL). ³Availablefrom Ashland Specialty Chemical (Wilmington, DE). ⁴Available fromSymrise AG (Branchburg, NJ). ⁵Sodium polyacrylate available fromVanderbilt Minerals LLC (Norwalk, CT). ⁶Polyacrylate available from TheDow Chemical Company (Lake Zurich, IL).

The table below shows the viscosity, PSD D50, and separation for eachexample. Properties such as viscosity, Particle Size Distribution (PSD),separation, loss modulus, and/or storage modulus can be used to evaluatewhether the cosmetic ink composition can be stable and jettable.Viscosity was measured after approximately 1 week from formulation andPSD D50 was measured after formulation and again after 4 weeks.Viscosity was measured according to the Viscosity Test Method describedhereafter. PSD was measured according to the Particle Size DistributionMethod described hereafter. Separation was measured according to theSeparation Test Method described hereafter. Separation is recorded inTable 2 as the number of days it took for the sample to reach 2 mm ofseparation, with the type of separation noted.

TABLE 2 First Wt % (Active) Dynamic PSD D50 Total Viscosity (nm)Separation Particulate Propylene Rheology Sodium 0.1 sec⁻¹ T = 4 at 50°C. Ex Material Glycol Modifier Polyacrylate cP T = 0 wks Days Type 110.00 20.00 0.25 0.11 1230 250 230 1 Syneresis 2 10.00 20.00 0.25 0.111430 260 240 1 Syneresis 3 10.00 20.00 0.33 0.21 1810 240 270 5Syneresis 4 10.00 20.00 0.33 0.00 29400 670 1,000 20 Syneresis 5 15.4420.00 0.46 0.11 9120 280 260 24 Syneresis 6 4.56 20.00 0.46 0.11 4950230 240 24 Syneresis 7 12.79 29.47 0.08 0.16 165 260 230 1 Settling 812.79 10.53 0.08 0.06 132 230 240 1 Settling 9 7.21 29.47 0.08 0.06 12240 230 1 Settling 10 7.21 10.53 0.08 0.16 3 270 230 0 Settling 11 6.943.46 0.32 0.15 1130 240 270 5 Syneresis 12 6.94 36.54 0.32 0.07 3920 230250 14 Syneresis 13 18.02 12.72 0.22 0.16 590 240 240 1 Settling 1418.02 27.28 0.22 0.06 2780 230 270 2 Syneresis 15 1.98 27.28 0.22 0.16333 260 230 0 Settling 16 1.98 12.72 0.22 0.06 391 250 220 0 Settling 1713.06 36.54 0.32 0.15 2880 240 240 11 Syneresis 18 13.06 3.46 0.32 0.073770 270 250 15 Syneresis

It was found that the most stable formulas contained 0.32 active wt %rheology modifier or more. Examples 3-6, 11-12, and 17-18, whichcomprised 0.32 active wt % rheology modifier or greater, each had afirst dynamic viscosity of greater than 1,100 cP and took 5-24 days toreach 2 mm of separation with syneresis observed, demonstrating that theformulas could build a sufficient internal structure to keep theparticles in suspension. Without being limited by theory, it is believedthat a sample demonstrating syneresis can still be stable because theparticles are uniformly distributed below the clear fluid layer. Incontrast, separation with settling in which the particles fall to thebottom of the sample may not be stable as the internal structure of thesample is not sufficient to suspend the particles.

Examples 3 and 4 demonstrate the need for both the rheology modifier andthe (meth)acrylic acid homopolymer sodium polyacrylate to achieve aviscosity and particle size suitable for jetting while maintainingparticle suspension. Examples 3 and 4 comprised 0.33 active wt %rheology modifier and a constant level of total particulate material andpropylene glycol. However, Example 3 had 0.21 active wt % (meth)acrylicacid homopolymer sodium polyacrylate while Example 4 had no(meth)acrylic acid homopolymer or salt thereof. Example 4 had betterseparation control as compared to Example 3; however, Example 4exhibited a first dynamic viscosity of 29,400 cP and poor control ofparticle size over 4 weeks as demonstrated by the increase in PSD D50.It is believed that the particle size and viscosity of Example 4 wouldnot be suitable for jetting.

Examples 5 and 6 had a constant level of propylene glycol, rheologymodifier, and (meth)acrylic acid homopolymer sodium polyacrylate, butvaried the level of total particulate material. Example 5 had a higherlevel of total particulate material as compared to Example 4 anddemonstrated a higher viscosity. However, both Example 5 and 6 took 24days to reach 2 mm of separation. Without being limited by theory, it isbelieved that the level of (meth)acrylic acid homopolymer or saltthereof and rheology modifier needed for particle size control andparticle suspension may not depend on the particulate material level. Itis believed that as long as the rheology modifier is present with someamount of particulate material, a weak colloidal gel can be formed.

In a separate experiment, different formulas were prepared to furtherassess the impact of the (meth)acrylic acid homopolymer or salt thereofand rheology modifier on the viscosity and separation of the cosmeticink composition. Examples 19-22 were made according to the proceduredescribed hereafter. Example 19 illustrates a cosmetic ink compositioncontaining a (meth)acrylic acid homopolymer sodium polyacrylate (Darvan®811D) and a HASE type rheology modifier (ACULYN™ Excel). Example 20 is acomparative example containing no rheology modifier. Example 21 is acomparative example containing no (meth)acrylic acid homopolymer or saltthereof. Example 22 is a comparative example containing a C12/C14 amineoxide as the rheology modifier.

Examples 19-22 were made according to the following formulas. Weightpercent is shown as added.

TABLE 3 19 20 21 22 Phase Description wt % wt % wt % wt % A 75 wt % TiO₂Slurry 12.18 11.54 12.18 15.81 (WPG75PFSP)¹ A 45 wt % Iron Oxide Slurry1.78 2.82 1.78 2.31 (WPG45GYSP)¹ A 55 wt % Iron Oxide Slurry 0.11 0 0.110 (WPG55GRSP)¹ A 45 wt % Iron Oxide Slurry 0 0.14 0 0.20 (WPG45SIRSP)¹ BDeionized Water 57.53 60.30 61.73 53.98 B PuraGuard ™ Propylene 20.0020.00 20.00 22.00 Glycol² B 50 wt % PVP/VA 735W³ 1.00 0 1.00 0 copolymerin water B Symdiol ® 68⁴ 1.00 1.00 1.00 0 C 5 wt % Darvan ® 811D⁵ 4.204.20 0 2.90 in water D 15 wt % ACULYN ™ Excel⁶ 2.20 0 2.20 0 in water D15% C12/C14 Amine Oxide⁷ 0 0 0 2.80 ¹Supplied by KOBO Products Inc(South Plainfield, NJ). ²Available from The Dow Chemical Company (LakeZurich, IL). ³Available from Ashland Specialty Chemical (Wilmington,DE). ⁴Hexanediol/Caprylyl Glycol available from Symrise AG (Branchburg,NJ). ⁵Sodium polyacrylate available from Vanderbilt Minerals LLC(Norwalk, CT). ⁶Polyacrylate available from The Dow Chemical Company(Lake Zurich, IL). ⁷Available from The Dow Chemical Company (LakeZurich, IL).

The samples were stored in sealed glass jars at 50° C. untilmeasurements were performed. The table below shows the PSD, viscosity,tan(delta), and separation for each example. Example 22 was tested at adifferent time; however, the data are shown together for ease ofcomparison. PSD is measured according to the Particle Size DistributionMethod described hereafter. Viscosity was measured according to theViscosity Test Method described hereafter. Tan(delta) was calculated byusing the storage modulus and loss modulus measured according to theOscillatory Strain Sweep Method described hereafter. Separation wasmeasured according to the Separation Test Method described hereafter.Separation is recorded in Table 4 as the number of days it took for thesample to reach 2 mm of separation, with the type of separation noted.

TABLE 4 Rheology First Second Modifier Sodium PSD PSD Dynamic DynamicSeparation at wt % Polyacrylate D50 D90 Viscosity Viscosity tan 50° C.Ex (active) wt % (active) (nm) (nm) 0.1 s⁻¹ (cP) 1000 s⁻¹ (cP) deltaDays Type 19 0.33 0.21 390 660 1810 35 0.62 5 Syneresis 20 0 0.21 390640 125 2 4.11 <1 Settling 21 0.33 0 1730 3560 29400 91 0.21 20Syneresis 22 0.42 0.145 4440 1200 110 4 5.17 2 Settling

Example 19, which contained 0.33 active wt % HASE rheology modifier and0.21 active wt % (meth)acrylic acid homopolymer sodium polyacrylate, hada first dynamic viscosity of 1,810 cP and a second dynamic viscosity of35 cP, demonstrating that the formula had shear thinning behavior. Inaddition, Example 19 had agglomeration control as the PSD D90 wasmaintained under Finally, Example 19 had a tan(delta) below 1 and took 5days to reach 2 mm of separation with syneresis observed.

Comparative Example 20, which contained 0.21 active wt % (meth)acrylicacid homopolymer sodium polyacrylate and no rheology modifier, had aparticle size distribution D90 under 1 μm. However, Comparative Example20 had a first dynamic viscosity of only 125 cP and was not as shearthinning as compared to Example 19. Comparative Example 20 reached 2 mmof separation in less than 1 day with settling observed. It is believedthat without the rheology modifier, the formula could not build enoughviscosity to suspend the particles.

It has been previously reported that the HASE rheology modifier ACULYN™Excel can provide a thixotropic ink composition that is jettable.However, it was found that although Comparative Example 21, whichcontained 0.33 active wt % ACULYN™ Excel HASE rheology modifier and no(meth)acrylic acid homopolymer sodium polyacrylate, had shear thinningbehavior and good separation control at 50° C., it had a PSD D50 4.4times greater than Example 19, indicating poor particle size control.Comparative Example 21 had a PSD D50 of 1730 nm and a PSD D90 of 3560nm. It is known that the microfluidic channels in ink cartridges can bevery small, for example about from about 10 μm to about 25 μm. As such,it is believed that Comparative Example 21 would likely be difficult torefill in a standard printer ejection head because of the high viscosityand would likely clog the flow channels due to the presence of largerparticles. It is also believed that the particles in Comparative Example21 may not have the optimal size for opacity.

Comparative Example 22 contained 0.42 active wt % C12/C14 amine oxiderheology modifier and 0.145 active wt % (meth)acrylic acid homopolymersodium polyacrylate. It has been previously reported amine oxides mayprovide some yield stress and may help prevent settling of particles ina cosmetic ink composition. However, it was surprisingly found thatC12/C14 amine oxide in Comparative Example 22 did not build viscosity tothe same extent as Example 19 and reached 2 mm of separation in only 2days with settling observed, demonstrating that C12/C14 in this formulais not able to build sufficient viscosity to suspend the particles.

Rheology Modifier Study

Different formulas were tested to assess the impact of rheologymodifiers on particle settling. Base Formula 1 was prepared as describedhereinafter. Various rheology modifiers (see Table 6) were then added toBase Formula 1 to form Examples 23-35. Propylene Glycol was added toBase Formula 1 as a control (Example 35). Examples 23-35 were preparedas described hereinafter. Approximately 30 mL of the resulting mixturewas placed into a 40 mL vial and stored at ambient conditions.

Base Formula 1 was made according to the following formula. Weightpercent is shown as added.

TABLE 5 Phase Ingredient wt % A 75 wt % TiO₂ Slurry (WPG75PFSP)¹ 22.50 A45 wt % Iron Oxide Slurry (WPG45GYSP)¹ 3.30 A 55 wt % Iron Oxide Slurry(WPG55GRSP)¹ 0.20 B Deionized Water 46.00 B PuraGuard ™ PropyleneGlycol² 12.50 B 50 wt % Polyvinylpyrrolidone/vinyl acetate 1.50 (PVP)735W³ in water B Symdiol ® 68⁴ 1.00 C Deionized Water 10.00 D 5 wt %Darvan ® 811D⁵ in water 3.00 Total 100.00 ¹Supplied by KOBO Products Inc(South Plainfield, NJ). ²Available from The Dow Chemical Company (LakeZurich, IL). ³Available from Ashland Specialty Chemical (Wilmington,DE). ⁴1, 2 Hexanediol/Caprylyl Glycol available from Symrise AG(Branchburg, NJ). ⁵Sodium polyacrylate available from VanderbiltMinerals LLC (Norwalk, CT).

Examples 23-35 were held for 4 days at ambient conditions. Particlesettling was assessed for each example by measuring weight percentsolids at the top, middle, and bottom of the sample according to theParticle Settling Test Method described hereafter. Weight percent solidsis recorded in table 6 as the solids remaining after drying thevolatiles off.

The table below summarizes the results.

TABLE 6 Weight Percent Solids wt % Bottom Middle Top Ex RheologyModifier (active) Chemical Type (wt %) (wt %) (wt %) 23 ACRYSOL ™ TT615²0.2 HASE 45.0 1.0 1.0 24 ACRYSOL ™ TT615² 0.4 HASE 14.3 14.4 5.5 25ACRYSOL ™ TT615² 0.6 HASE 18.0 16.3 15.9 26 ACULYN ™ Excel⁶ 0.4HASE/acrylates 18.1 17.8 17.7 copolymer 27 ACULYN ™ 38² 0.4ASE/acrylates 57.1 1.3 1.8 niodecanoate crosspolymer 28 ACRYSOL ™ TT935²0.2 HASE 42.9 1.2 1.3 29 ACRYSOL ™ TT935² 0.4 HASE 26.9 1.4 1.2 30ACRYSOL ™ TT935² 0.6 HASE 16.0 1.8 2.1 31 Natrosol ™ 250 HHR⁸ 0.4Hydroxyethyl cellulose 24.4 2.6 1.2 32 Stabylen 30⁹ 0.2 Acrylates/Vinyl21.9 10.3 3.2 Isodecanoate Crosspolymer 33 Carbopol ® Ultrez 21¹⁰ 0.2Hydrophobically modified 17.9 12.0 4.1 crosslinked polyacrylate 34Aristoflex ® HMB¹¹ 0.5 Ammonium 43.2 3.9 2.6 Acryloyldimethyltaurate/Beheneth-25 Methacrylate Crosspolymer 35 PuraGuard ™ 10.0 Glycol 20.914.9 2.0 Propylene Glycol² ²Available from The Dow Chemical Company(Lake Zurich, IL). ⁶Polyacrylate available from The Dow Chemical Company(Lake Zurich, IL). ⁸Available from Ashland (Covington, KY). ⁹Availablefrom 3V Sigma (Georgetown, SC). ¹⁰Available from Lubrizol (Wickliffe,OH). ¹¹Available from Clariant Corp. (Blue Ash, OH).

It was found that Example 23, which contained 0.2 active wt % ACRYSOL™TT615, did not build sufficient viscosity and particle settling tookplace over the 4 day period, as demonstrated by the differing weightpercent solids content from top to bottom. However, it was found that asthe concentration of ACRYSOL™ TT615 increased, particle settlingstability increased. Examples 24 and 25, which comprised 0.4 and 0.6active wt % ACRYSOL™ TT615, respectively, built sufficient viscosity andthe particles did not significantly settle over the 4 day period,although some syneresis was observed. It was found that the weightpercent solids content from top to bottom was consistent for Example 26,indicating that the particles did not significantly settle over the 4day period.

Examples 26 comprised 0.4 active wt % of the HASE polymer ACULYN™ Excel.It was found that the Example 28-30 formulations, which comprised theHASE class polymer ACRYSOL™ TT935, were not able to build sufficientviscosity within the composition and solids settling took place over the4 day period. Without being limited by theory, it is believed that thisparticular HASE polymer may not have sufficient charge density and mayhave too much hydrophobicity to build the viscosity needed to maintainstability and limit particle settling. However, it is believed that athigher concentrations this rheology modifier may be able to thicken thecosmetic ink composition and build a sufficient viscosity to suspend theparticles. Example 27, which comprised the ASE class polymer ACULYN™ 38showed substantial particle settling over the 4 day period. It isbelieved that adjusting the level of ACULYN™ 38 ASE polymer can improvethe suspension of solids and reduce the particle settling. Finally,Examples 31-35 are comparative examples which showed substantialvariation in the solids content from top to bottom indicating thatparticle settling took place over the 4 day period.

In a separate study, different formulas were tested to assess the impactof various types of ASE, HASE, and HEUR polymer rheology modifiers onviscosity and separation of the cosmetic ink composition. Examples 36-48were prepared according to the procedure described hereinafter.

Examples 36-48 were made according to the formulas in the tables below.Weight percent is shown as added.

TABLE 7 36 37 38 39 40 Phase Ingredient wt % wt % wt % wt % wt % A 75 wt% TiO2 Slurry 18.46 18.46 15.00 15.00 15.00 (WPG75PFSP) ¹ A 45 wt % IronOxide Slurry 4.51 4.51 3.67 3.67 3.67 (WPG45GYSP) ¹ A 45 wt % Iron OxideSlurry 0.29 0.29 0.22 0.22 0.22 (WPG45SIRSP) ¹ A Deionized Water 10.0010.00 10.00 10.00 10.00 B Deionized Water 37.8 37.14 43.51 40.51 39.90 BPuraGuard ™ Propylene Glycol² 23.00 23.00 23.00 23.00 23.00 C 5 wt %Darvan ® 811D⁵ 2.60 2.60 2.60 4.00 4.00 in water D 15 wt % ACRYSOL ™TT615² 3.33 0 0 0 0 in water D 15 wt % Rheovis ® AS1125¹² 0 3.33 0 0 0in water D 15 wt % ACULYN ™ Excel⁶ 0 0 2.00 0 0 in water D 15 wt %ACULYN ™ 22² in 0 0 0 3.60 0 water D 15 wt % ACULYN ™ 33² in 0 0 0 03.93 water 41 42 43 44 45 Phase Ingredient wt % wt % wt % wt % wt % A 75wt % TiO2 Slurry 15.00 15.00 15.00 15.00 15.00 (WPG75PFSP) ¹ A 45 wt %Iron Oxide Slurry 3.67 3.67 3.66 3.66 3.66 (WPG45GYSP) ¹ A 45 wt % IronOxide Slurry 0.22 0.22 0.22 0.22 0.22 (WPG45SIRSP) ¹ A Deionized Water10.00 10.00 10.00 10.00 10.00 B Deionized Water 40.31 39.11 39.60 40.5237.72 B PuraGuard ™ Propylene Glycol² 23.00 23.00 23.00 23.00 23.00 C 5wt % Darvan ® 811D⁵ 4.00 4.00 4.00 4.00 4.00 in water D 15 wt % ACULYN ™38² 3.80 0 0 0 0 in water D 15 wt % ACULYN ™ 88² 0 5.00 0 0 0 in water D15 wt % Rheovis ® 1152¹² 0 0 4.53 0 0 in water D 15 wt % Rheovis ®1156¹² 0 0 0 3.60 0 in water D 15 wt % ACRYSOL ™ TT935² 0 0 0 0 6.40 inwater 46 47 48 Phase Ingredient wt % wt % wt % A 75 wt % TiO2 Slurry(WPG75PFSP) ¹ 15.00 15.00 15.00 A 45 wt % Iron Oxide Slurry (WPG45GYSP)¹ 3.66 3.66 3.66 A 45 wt % Iron Oxide Slurry (WPG45SIRSP) ¹ 0.22 0.220.22 A Deionized Water 10.00 10.00 10.00 B Deionized Water 40.26 32.1832.18 B PuraGuard ™ Propylene Glycol² 23.00 23.00 23.00 C 5 wt %Darvan ® 811D⁵ in water 4.00 2.60 2.60 D 15 wt % ACRYSOL ™ DR300²solution 3.86 0 0 D 15 wt % ACULYN ™ 44² in water 0 12.40 0 D 15 wt %ACULYN ™ 46N² in water 0 0 12.47 ¹ Supplied by KOBO Products Inc (SouthPlainfield, NJ). ²Available from The Dow Chemical Company (Lake Zurich,IL). ⁵Sodium polyacrylate available from Vanderbilt Minerals LLC(Norwalk, CT). ⁶Polyacrylate available from The Dow Chemical Company(Lake Zurich, IL). ¹²Available from BASF (Florham Park, NJ).

The samples were stored in sealed glass jars at 25° C. or 40° C. untilmeasurements were performed. The table below shows the viscosity,tan(delta), and separation measured 11 days after formulation for eachexample. Viscosity was measured according to the Viscosity Test Methoddescribed hereafter. Tan(delta) was calculated using the storage modulusand loss modulus measured according to the Oscillatory Strain SweepMethod described hereafter. Separation was measured according to theSeparation Test Method described hereafter.

TABLE 8 Sodium Rheology Modifier Polyacrylate Viscosity Separation at 11days wt % wt % 0.1 s⁻¹ 1000 s⁻¹ tan 25° C. 40° C. Ex Name Type (active)(active) (cP) (cP) (delta) (mm) (mm) Type 36 ACRYSOL ™ TT615 HASE 0.500.13 6290 76 0.61 1 16 Syneresis 37 Rheovis ® AS1125 ASE 0.50 0.13 204073 0.68 2 3 Syneresis 38 ACULYN ™ Excel HASE 0.30 0.13 3180 37 0.54 0 0none 39 ACULYN ™ 22 HASE 0.54 0.2 4670 71 0.43 0 14 Syneresis 40ACULYN ™ 33 ASE 0.59 0.2 4040 63 0.41 0 0 none 41 ACULYN ™ 38 ASE 0.570.2 2280 42 0.49 0 1.5 Syneresis 42 ACULYN ™ 88 HASE 0.75 0.2 4320 710.50 0.5 1.5 Syneresis 43 Rheovis ® 1152 HASE 0.68 0.2 3060 80 0.95 3.525 Syneresis 44 Rheovis ® 1156 HASE 0.54 0.2 1290 69 1.77 21 40Syneresis 45 ACRYSOL ™ TT935 HASE 0.96 0.2 763 61 1.89 37 46 Syneresis46 ACRYSOL ™ DR300 ASE 0.58 0.2 624 43 1.64 43 49.5 Syneresis 47ACULYN ™ 44 HEUR 1.86 0.13 194 22 3.30 46 49.5 Settling 48 ACULYN ™ 46NHEUR 1.87 0.13 460 32 4.15 48 52 Settling

For both ASE and HASE polymers, it is believed that the interaction ofthe anionic moiety of the rheology modifier with the particle surfaceand the (meth)acrylic acid homopolymer or salt thereof can promotestability. This forms a weak colloidal gel by introducing elasticity inthe composition (as demonstrated by the storage modulus of the cosmeticink composition) along with viscosity (as demonstrated by the lossmodulus of the cosmetic ink composition). Particle suspension can beachieved for cosmetic ink compositions having a low ratio of G″ to G′,i.e. a tan(delta) of preferably less than about 1, more preferably lessthan about 0.60.

It was found that Examples 36-43, which all had a first dynamicviscosity of greater than 1,100 cP and a tan(delta) of less than 1, hadless than 4 mm of separation at 11 days at 25° C. with syneresisobserved. Under accelerated temperature conditions, Examples 36-43 had25 mm of separation or less at 11 days with syneresis observed. Examples38 and 40 had no separation at 11 days under both temperature conditionstested.

Although Example 44 had a first dynamic viscosity of 1,290 cP that fallswithin the preferred range, the tan(delta) was greater than 1 and 21 mmof separation was observed at 11 days. Examples 45 and 46 contained HASEand ASE type rheology modifiers, respectively. However, Examples 45 and46 were not able to build a sufficient viscosity to suspend theparticles, as demonstrated by the first dynamic viscosity of well below1,100 cP and the mm of separation at both temperature conditions.Without being limited by theory, it is believed that these formulas werenot able to form a strong enough colloidal gel to keep the particles insuspension because the formulations comprised too many hydrophobicmoieties. Finally, Examples 47 and 48, which contained HEUR typerheology modifiers, had a first dynamic viscosity of less than 500 cPand a tan(delta) of well above 1. Examples 47 and 48 were not able tobuild sufficient viscosity to suspend the particles and had over 45 mmof separation at 11 days with particle settling observed under bothtemperature conditions. Not wishing to be bound by theory, it isbelieved that HEUR polymers may not be able to build sufficientelasticity and/or viscosity in the cosmetic ink composition to keep theparticles suspended.

Examples 1-22 were made according to the following procedure.

First, the ingredients of Phase A were combined in an appropriate premixcontainer and mixed for 30 minutes. The ingredients of Phase B wereadded into a main container. Phase B was mixed using a mixer with apropeller blade, such as a digital Eurostar 400® available from IKA®(Staufen im Breisgau, Germany) or equivalent, at low speed until themixture was homogenous. The pH of the Phase B mixture was measured.Then, the contents of the premix container were transferred into themain container and mixed for 30 minutes. Approximately 10% of the waterwas withheld from Phase B and was used to wash the premix container andthen added to the main container while mixing. Phase C was added to themain container. The mixing speed was increased to high speed and mixingcontinued for 10 minutes. Phase D was then added dropwise to the maincontainer and the pH was maintained between 7.5-8.5 by adding 20% KOH.Homogeneity was ensured and the mixture was poured into a container,labeled, and stored at ambient conditions before use.

Examples 23-35 were made according to the following procedure.

First, Base Formula 1 was prepared. The ingredients of Phase A werecombined in an appropriate premix container. The ingredients of Phase Bwere added into a main container. Phase B was mixed using a mixer with apropeller blade, such as a digital Eurostar 400® available from IKA®(Staufen im Breisgau, Germany), or equivalent, at low speed until themixture was homogenous. While mixing, Phase A was added into the maincontainer. Phase C was added to the premix container to wash out thecontainer and then added to the main container while mixing continued.The mixing speed was increased to high speed and mixing continued for 10minutes. Phase D was then added to the main container and mixed for 15minutes to form Base Formula 1. Homogeneity was ensured and Base Formula1 was poured into a container. In separate containers, the rheologymodifiers were prepared as solution in water. Each rheology modifier waspremixed in deionized water at 15 wt % and then added to Base Formula 1at the active wt % levels described in table 6 while adjusting the pH toapproximately 8 with 20% KOH.

Examples 36-48 were prepared according to the following procedure.

First, the ingredients of Phase A were combined in an appropriate premixcontainer and mixed for 30 minutes. The ingredients of Phase B wereadded into a main container. Phase B was mixed using a mixer with apropeller blade, such as a digital Eurostar 400® available from IKA®(Staufen im Breisgau, Germany) or equivalent, at low speed until themixture was homogenous. The pH of the Phase B mixture was measured.Then, the contents of the premix container were then transferred intothe main container and mixed for 30 minutes. Phase C was added to themain container and mixed. The pH of the main container was measured.Phase D was added to the main container dropwise and the pH wasmaintained between 7.5-8.5 by adding 20% KOH solution. Homogeneity wasensured and the mixture was poured into a container, labeled, and storedat ambient conditions before use.

Particle Size Distribution Method

The particle size distribution is determined using a laser scatteringparticle size distribution analyzer. A suitable laser scatteringparticle size distribution analyzer can include a Horiba LA-950V2(available from Horiba, Ltd., Kyoto, Japan). In this method, theprinciples of Mie and Fraunhofer scattering theories are used tocalculate the size and distribution of particles suspended in a liquid.Results are normally displayed on a volume basis. The application ofthis method to pigments has been developed using a flow cell procedure.

Samples are prepared by vortexing for 30 seconds with a Vortex Genie 2to ensure there is no residue in the bottom of the sample vial. 200 mLof deionized (DI) water is added into the instrument reservoir andanalyzed as a blank sample. A disposable micro pipet is used to dispenseenough sample into the DI water in the instrument until theTransmittance is reduced from 100 down to 90±2%, approximately 250 μL.Results are reported as D50 or D90.

Viscosity Test Method

Viscosity is measured using a rheometer as a function of shear rate. Asuitable rheometer can include an Ares M (available from TA Instruments,New Castle, Del.), or equivalent. First, the samples and standards areequilibrated at room temperature prior to analysis. A 50 mm, 2 degree,cone and plate is zeroed prior to testing. While the sample is at 25°C.±0.5° C., the sample is tested. A shear sweep measurement is performedover a range of 0.1-1000 s⁻¹ to determine the shear thinning propertiesand viscosity at different shear rates.

Separation Test Method

Separation is measured by filing an 8-dram (1 oz., 25 mm×95 mm) screwcap glass vial to a height of 55 mm with the sample composition (asmeasured from the bottom of the vial to the top of the liquidcomposition). The vials are sealed and are placed in controlledtemperature chambers. The vials are held static storage untilmeasurements are performed. At each time point, the vial is carefullyremoved from the chamber without vigorous or prolonged agitation andobserved for any visual signs of separation and the type of separationis noted as syneresis or settling. The amount of separation isdetermined by measuring the mm of clear fluid at the top of the samplewith a digital caliper.

Particle Settling Test Method

Particle settling is measured as follows. An aluminum dish is weighed todetermine the dish weight. A 1 gram aliquot of the sample from the top,middle, or bottom of the sample vial is added to the dish and weighed todetermine the wet weight. “Top” means the surface of the sample in thevial. “Middle” means the middle of the vial. “Bottom” means the bottomof the vial. The dish with the sample aliquot is placed in an oven at100° C. for one hour to evaporate the volatiles. The dish is removed andweighed again to get a dry weight. The weight % solids is calculated bythe following equation: (dry weight−dish weight)/(wet weight−dishweight).

Oscillatory Strain Sweep Method

Oscillatory strain sweep is measured using a rheometer (such as anARES-G2 available from TA Instruments, New Castle, Del.), or equivalent.

The samples and standards are allowed to equilibrate at ambientconditions prior to analysis. The rheometer is calibrated as disclosedin the operator's manual. The oscillatory strain sweep measurement isperformed at a fixed angular frequency of 6.28 rad/s over a strain rangeof 0.0001-1 using a 40 mm 316SST (APS heat break) parallel plate at 25°C., with a 0.05 mm gap, to determine the storage and loss moduli.

Zeta Potential Test Method

Zeta potential is measured using a Zeta potential analyzer such as aNanoBrook ZetaPALS Potential Analyzer available from BrookhavenInstruments Corporation, Holtsville, N.Y., or equivalent.

Zeta potential test samples are prepared by diluting the sample to 0.1g/ml into deionized water. Zeta potential is measured on a Zetapotential analyzer using the Smoluchowski Zeta potential model with 5runs and 10 cycles. After running a standard (BIZR3), the cells of theZeta potential analyzer are loaded with 1 ml of test sample. Zetapotential is measured as a function of pH.

Combinations

-   -   A. A cosmetic ink composition comprising: from about 1% to about        30 active wt % of a particulate material having a Particle Size        Distribution D50 of 100 nm to 2,000 nm; a (meth)acrylic acid        homopolymer or salt thereof having a weight average molecular        weight of less than 20,000 daltons; and a rheology modifier,        wherein the rheology modifier is selected from the group        consisting of alkali swellable emulsion polymers,        hydrophobically modified alkali swellable emulsion polymers, and        combinations thereof; wherein the cosmetic ink composition has a        first dynamic viscosity of greater than 1,100 cP at a shear rate        of 0.1 sec⁻¹ measured at 25° C. and a second dynamic viscosity        of less than 100 cP at a shear rate of 1,000 sec⁻¹ measured at        25° C.    -   B. The cosmetic ink composition of paragraph A wherein the        cosmetic ink composition has a first dynamic viscosity of 1,100        cP to 10,000 cP at a shear rate of 0.1 sec⁻¹ measured at 25° C.,        preferably 1,500 cP to 8,000 cP, more preferably from 2,000 cP        to 5,000 cP, and a second dynamic viscosity of from 10 to 100 cP        at a shear rate of 1,000 sec⁻¹ measured at 25° C., preferably        from 20 to 80 cP.    -   C. The cosmetic ink composition of paragraph A or B, wherein the        cosmetic ink composition comprises greater than 0.30 active wt %        rheology modifier.    -   D. The cosmetic ink composition of any of the preceding        paragraphs comprising from 0.01 to 1 active wt % (meth)acrylic        acid homopolymer or salt thereof, preferably from 0.10 to 0.85        active wt %, more preferably from 0.20 to 0.75 active wt %.    -   E. The cosmetic ink composition of any of the preceding        paragraphs wherein cosmetic ink composition comprises a ratio of        (meth)acrylic acid homopolymer or salt thereof to rheology        modifier of from 0.1 to 0.75, preferably from 0.30 to 0.65.    -   F. The cosmetic ink composition of any of the preceding        paragraphs wherein the cosmetic ink composition further        comprises from 20 to 30 active wt % humectant.    -   G. The cosmetic ink composition of any of the preceding        paragraphs wherein the rheology modifier is an alkali swellable        acrylic polymer emulsion.    -   H. The cosmetic ink composition of any of the preceding        paragraphs wherein the (meth)acrylic acid homopolymer or salt        thereof is sodium polyacrylate.    -   I. The cosmetic ink composition of any of the preceding        paragraphs wherein the (meth)acrylic acid homopolymer or salt        thereof has a weight average molecular weight of from 2,000 to        5,000 daltons.    -   J. The cosmetic ink composition of any of the preceding        paragraphs wherein the cosmetic ink composition has a neat pH of        from 7.5 to 9.0.    -   K. The cosmetic ink composition of any of the preceding        paragraphs wherein the particulate material has a Particle Size        Distribution D50 of from 150 nm to 1,000 nm, preferably from 200        nm to 500 nm, and more preferably from about 200 nm to about 350        nm.    -   L. The cosmetic ink composition of any of the preceding        paragraphs the wherein particulate material has a Particle Size        Distribution D90 of from 700 nm to 900 nm.    -   M. The cosmetic ink composition of any of the preceding        paragraphs wherein the particulate material is selected from the        group consisting of a pigment, a metal oxide, a colorant, a dye,        a clay, and combinations thereof.    -   N. The cosmetic ink composition of any of the preceding        paragraphs wherein the cosmetic ink composition further        comprises one or more skin care actives selected from the group        consisting of niacinamide; inositol; undecylenoyl phenylalanine;        and combinations thereof.    -   O. The cosmetic ink composition of any of the preceding        paragraphs wherein the cosmetic ink composition further        comprises a preservative.    -   P. The cosmetic ink composition of any of the preceding        paragraphs further comprising a monohydric alcohol selected from        the group consisting of methanol, ethanol, 1-propanol,        2-propanol, 1-butanol, 2-butanol, 2-methyl-1-propanol,        2-methyl-2-propanol and mixtures thereof.

Values disclosed herein as ends of ranges are not to be understood asbeing strictly limited to the exact numerical values recited. Instead,unless otherwise specified, each numerical range is intended to meanboth the recited values and any integers within the range. For example,a range disclosed as “1 to 10” is intended to mean “1, 2, 3, 4, 5, 6, 7,8, 9, and 10.”

The dimensions and values disclosed herein are not to be understood asbeing strictly limited to the exact numerical values recited. Instead,unless otherwise specified, each such dimension is intended to mean boththe recited value and a functionally equivalent range surrounding thatvalue. For example, a dimension disclosed as “40 mm” is intended to mean“about 40 mm.”

Every document cited herein, including any cross referenced or relatedpatent or application and any patent application or patent to which thisapplication claims priority or benefit thereof, is hereby incorporatedherein by reference in its entirety unless expressly excluded orotherwise limited. The citation of any document is not an admission thatit is prior art with respect to any invention disclosed or claimedherein or that it alone, or in any combination with any other referenceor references, teaches, suggests or discloses any such invention.Further, to the extent that any meaning or definition of a term in thisdocument conflicts with any meaning or definition of the same term in adocument incorporated by reference, the meaning or definition assignedto that term in this document shall govern.

While particular embodiments of the present invention have beenillustrated and described, it would be obvious to those skilled in theart that various other changes and modifications can be made withoutdeparting from the spirit and scope of the invention. It is thereforeintended to cover in the appended claims all such changes andmodifications that are within the scope of this invention.

What is claimed is:
 1. A cosmetic ink composition comprising: a. fromabout 1 to about 30 active wt % of a particulate material having aParticle Size Distribution D50 of about 100 nm to about 2,000 nm; b. a(meth)acrylic acid homopolymer or salt thereof; and c. a rheologymodifier, wherein the rheology modifier is selected from the groupconsisting of alkali swellable emulsion polymers, hydrophobicallymodified alkali swellable emulsion polymers, and combinations thereof;wherein the cosmetic ink composition has a first dynamic viscosity ofgreater than about 1,100 cP at a shear rate of 0.1 sec⁻¹ measured at 25°C. and a second dynamic viscosity of less than about 100 cP at a shearrate of 1,000 sec⁻¹ measured at 25° C.
 2. The cosmetic ink compositionof claim 1, wherein the particulate material has a Particle SizeDistribution D90 of from about 700 nm to about 900 nm.
 3. The cosmeticink composition of claim 1 wherein the particulate material comprises ametal oxide.
 4. The cosmetic ink composition of claim 3 wherein theparticulate material comprises titanium dioxide.
 5. The cosmetic inkcomposition of claim 4 wherein the titanium dioxide is substantiallycoated with a coating ingredient selected from silica, alumina, andcombinations thereof.
 6. The cosmetic ink composition of claim 1,wherein the cosmetic ink composition comprises greater than about 0.30active wt % rheology modifier.
 7. The cosmetic ink composition of claim1 further comprising one or more skin care actives selected from thegroup consisting of niacinamide, inositol, undecylenoyl phenylalanine,and combinations thereof.
 8. The cosmetic ink composition of claim 1wherein the ink composition has a tan(delta) of from about 0.01 toabout
 1. 9. The cosmetic ink composition of claim 1 further comprising apreservative.
 10. The cosmetic ink composition of claim 1 wherein thecosmetic ink composition further comprises from about 10 to about 30active wt % of a humectant.
 11. The cosmetic ink composition of claim 10wherein the cosmetic ink composition comprises from about 20 to about 30active wt % of a humectant.
 12. The cosmetic ink composition of claim 1,wherein the cosmetic ink composition comprises from about 0.3 to about 1active wt % of the rheology modifier.
 13. The cosmetic ink compositionof claim 1, wherein the cosmetic ink composition has a first dynamicviscosity of about 1,100 cP to about 10,000 cP at a shear rate of 0.1sec⁻¹ measured at 25° C. and a second dynamic viscosity of from about 10to about 100 cP at a shear rate of 1,000 sec⁻¹ measured at 25° C. 14.The cosmetic ink composition of claim 1 wherein the cosmetic inkcomposition comprises from about 0.01 to about 1 active wt % of the(meth)acrylic acid homopolymer or salt thereof.
 15. The cosmetic inkcomposition of claim 1 wherein the (meth)acrylic acid homopolymer orsalt thereof is sodium polyacrylate.
 16. The cosmetic ink composition ofclaim 1, wherein the particulate material has a Particle SizeDistribution D50 of from about 200 nm to about 350 nm.
 17. The cosmeticink composition of claim 1 wherein the (meth)acrylic acid homopolymer orsalt thereof has a a weight average molecular weight of less than about20,000 daltons.
 18. The cosmetic ink composition of claim 18 wherein the(meth)acrylic acid homopolymer or salt thereof has a weight averagemolecular weight of from about 2,000 to about 5,000 daltons.